Windows steam up suddenly while driving!
 

Hoping someone can help me. It feels like my car is trying to kill me! I am driving along with the A/C on when suddenly it changes onto the A/C being switched off and a blast of very hot, damp air, like a sauna, fills the car. All the windows steam up in seconds and I'm left with zero visibility in any window. I can't see the hood never mind the road! I can't even pull off the road as I can't see it! I desperately reach forward and clear a tiny patch to see through but still can't pull over as I cant see the curb or if any cars are beside me. Then the next time I get into the car it is fine again and doesn't do it again for maybe a year! When it gets like this, I try pressing the A/C on again but the light just flashes then goes off again. Does anyone know what is causing this?
Any help greatly appreciated.
Cheers,
Jilly Bean

Frequently happens to me at night when I get to the top of a 4200 ft. pass near my house. It happens suddenly, but the defrosters take care of it. I think the use of outside air will keep your a/c on and help with this problem.

After thinking about it a little more, I believe that in my case the warmer air inside the car holds more moisture. When I get into colder air at a higher altitude, the cold air can't hold as much moisture and the moisture percipitates out of the inside air onto the inside of the windows.

Thanks for the reply Binski but I live in Florida so have the A/C blowing cool air when it suddenly switches to this awful steamy air. It is not the air from outside being too hot as it happened to me tonight and the outside air temp was a chilly 58F. I guess I'll have to hope my local garage will be able to fix it (I refuse to use the dealership near me, they don't have a clue what they are doing!)

Check to ensure your evaporator housing condensate drain is draining properly. It's located on the bulkhead behind the engine, above the starter and behind the passensenger side cylinder head. If it's plugged, it will cause the type of problems you are describing.

are you near Orlando?

If you are speaking to me, the answer is yes.

Thanks for the info Ipuig, I'll have a look at it tomorrow in daylight and see if I can see it.

Yes, I am. I live close to Disney.

pull the codes using the DIC http://www.stengel.net/diccodes.htm before you go to the shop, post codes here and maybe you could get some more info. At least you'd have some info to take to the shop....good luck.... I'm sure you will have some 99-HVAC codes something ain't stirring the kool-aid:crazy:

Thanks 02KoolC5. I'll give that a try tomorrow.

Mine will do this but only after a full throttle run at the drag strip on decell and has only happened under those conditions

When you run the A/C system, the condenser inside the car gets cold and collects all the moisture out of the air - ie, A/C runs when the defroster is on and effectively dehumidifies the air inside the cabin.

Sounds like for some reason your A/C system shuts off, and then what happens is all that captured moisture on the condenser evaporates off suddenly and fogs up the interior. I'm guessing you are running the A/C on "recirculation" mode also? If so, that might make it worse than not.

If it happens again, roll both windows down ASAP and switch to outside air if you're running on recirculation mode with A/C. That should help clear the fogged up windshield quickly.

Hopefully pulling codes will give you a clue on why it switches out of A/C on it own.

Thanks ZeeOSix. Yes, I do have it in recirculation mode when it happens. My passenger side window is not working at the moment so I can't get a through draft going, which I'm sure would help. It is also like it switches to a different mode when it does this and it also cranks up the blowers to full on when it does it. It is a really horrible experience and I have to give so much attention just to try to drive and clear a patch to see through that I don't have time to concentrate on what the settings are doing. Anyway, I'll pull the codes tomorrow and see if that shows up something. Even if I can't fix it myself it would probably be helpful when speaking to a mechanic. Thanks for the tip about the condenser evaporating off.

Sorry to hear your's does that too sometimes. Unfortunately mine just happens under normal driving conditions. It must be fun to drag it though!

Certainly sounds like water trapped in the system. Check the udders as already suggested and also try keeping it out of the recirc mode

There are 5 different codes showing

99VAC B0367H Right Actuator Feedback Open

BORFA U1096H Loss Of Communication With IPC
U1064H Loss Of Communication With BCM
U1016H Loss Of Communication With PCM

58SDM B1001H ( I don't know what this code means)

I don't know if this is relevant to the codes or not but recently I fitted a CLB (Column Lock Bypass) and took out the K Harness that GM had fitted. My car had been drivable with the steering lock on!!! I think I cleared all the codes after I did that. The problem after that was with my alternator and I had a new one fitted.

Time to check the right floorboard for signs of moisture, specifically the carpet where the passengers feet are.

I had a look to see if I could spot it and I'm sorry to be such a 'girl' about it, but I couldn't tell which pipe to look at! But I'll take it to a mechanic and tell him what you said and I'm sure he'll know. Fitting a CLB was about the limit of my talent these days and that was only because of the wonderful help from guys from this sight like Chuck who talked me through it.

Thanks Lucky131969 for the suggestion,
I just checked and it is as dry as a bone with no signs of any past water leaking in either.